1. Field of the Invention
The invention relates to modular construction systems and more particularly to such systems in which the modules are polygonal elements of stiff sheet material formed to interlock with each other in a unique and novel manner to form three dimensional structures.
2. The Prior Art
The prior art includes a number of construction systems utilizing card-like modules or elements of geometric or polygonal shape as exemplified by Harold A. Battjes U.S. Pat. No. 2,075,259 in which rectangular cards are fastened to each other by rectangular ears projecting from their edges into slits in the other cards; B. Cooley U.S. Pat. No. 2,454,307 in which generally oval projections on two adjacent edges of square cards fit into slots elongated along the other edges of the cards and having straight outer edges and arcuate inner edges; N. E. Bessinger U.S. Pat. No. 3,120,078 discloses polygonal panels with inwardly directed pegs projecting from the plane of each panel adjacent each side thereof, with elastic bands connecting the pegs to join the panels to each other; Ehrlich U.S. Pat. No. 3,998,004 discloses triangular panels with magnetic flaps for securing them to each other; E. H. Harvey U.S. Pat. No. 4,055,019 dicloses square and triangular panels with projections from their sides forming hinge-like connections; J. F. Walker U.S. Pat. No. 4,212,130 discloses a modular playhouse in which the modules are secured to each other by separate bendable strips with their ends inserted into slits adjacent the sides of the respective modules; and A. A. Mayr U.S. Pat. No. 4,253,268 discloses square, triangular and rectangular panels with cooperating ball and scoket connections between them.